[0001] This invention relates to a contacts material for a vacuum valve, vacuum valves per
se and methods of manufacturing them.
[0002] The most important properties which contacts material for vacuum valves is required
to have are the three basic requirements of anti-welding property, voltage withstanding
capability and current interrupting property. Further important requirements are to
show low and stable rise in temperature and low and stable contact resistance. However,
it is not possible to satisfy all these requirements by a single metal, as some of
them are contradictory. Consequently, many of the contacts materials that have been
developed for practical use consist of combinations of two or more elements so as
to complement their mutual deficiencies in performance, and to match specific applications
such as large-current use or high voltage-withstanding ability. However, performance
requirements have become increasingly severe and the present situation is that these
materials are unsatisfactory in some respects. A marked recent tendency is expansion
of the use of these materials to capacitor circuits. Corresponding development and
improvement of contacts materials is an urgent task.
[0003] In order to cope with this, contacts materials have previously been employed consisting
of copper, as conductive constituent, combined with tungsten, molybdenum, tantalum
or niobium, which are high melting point materials and in general provide excellent
withstand-voltage capability.
[0004] Such Cu-W or the like contacts materials can be applied in fields where a certain
degree of withstand-voltage performance is required. However, they are subject to
the problem of restriking in more severe high withstand-voltage regions and circuits
in which inrush currents occur. The reason for this is insufficient adhesive strength
between the grains of the arc-proof material and the conductive constituent, owing
to insufficient wetting of the arc-proof material by the conductive constituent.
[0005] Specifically, restriking occurs, even though the electrodes are in open condition,
because particles of arc-proof material get electrically charged and are discharged
from the surface of the contacts, and because gas is emitted from pores produced in
the interior of the contacts by insufficient wetting. Furthermore, when local welding
takes place due to radio frequency currents etc. generated when the circuit is closed,
since the interface between the aforementioned arc-proof material and conductive constituent
is weak and local pores are present, transfer to the contacts surface occurs when
the electrodes are separated. This causes electric field concentrations etc., which
may result in restriking. Such restriking may cause malfunction of the circuit system,
resulting for example in cut-off of power. In particular, in capacitor circuits, a
voltage of twice the ordinary circuit voltage is applied, so the problem of the withstand-voltage
characteristic of the contacts, in particular, suppression of restriking has become
prominent.
[0006] As described above, the reason for occurrence of restriking is insufficient strength
of adhesion between the grains of arc-proof material and the conductive constituent,
due to insufficient wetting of the arc-proof material with the conductive constituent.
It is therefore vital to reduce the frequency of occurrence of restriking by increasing
the interface strength and reducing internal pores.
[0007] Accordingly, one object of this invention is to provide a contacts material for a
vacuum valve, whereby the frequency of occurrence of restriking is reduced.
[0008] Another object of this invention is to provide a method of manufacturing a contacts
material for a vacuum valve, whereby the frequency of occurrence of restriking is
reduced.
[0009] In order to achieve the aforementioned object, the essence of this invention consists
in the addition to the arc-proof constituent and conductive constituent of an auxiliary
constituent consisting of at least one of chromium, titanium, yttrium, zirconium,
cobalt, and vanadium, in order to strengthen adhesion of the arc-proof constituent
and conductive constituent.
[0010] These and other objects of this invention can be achieved by providing a contacts
material for vacuum valve including an arc-proof constituent having at least one selected
from the group consisting of tantalum, niobium, tungusten and molybdenum and an auxiliary
constituent having at least one selected from the group consisting of chromium, titanium,
yttrium, zirconium, cobalt and vanadium. The contact material further includes a conductive
constituent having at least one selected from the group consisting of copper and silver.
An amount of the arc-proof constituent is from 25% to 75% by volume. A total amount
of the arc-proof constituent together with the auxiliary constituent is no more than
75% by volume. And an amount of the conductive constituent is the balance.
[0011] These and other objects of this invention can further be achieved by providing a
method of manufacturing the contacts material as described above including the step
of manufacturing a skeleton with the arc-proof constituent and the auxiliary constituent.
The method further includes the step of infiltrating the skeleton with an infiltration
material to obtain the contacts material.
[0012] These and other objects of this invention can further be achieved by providing a
method of manufacturing the contacts material as described above including the step
of manufacturing a skeleton with the arc-proof constituent, the auxiliary constituent
and the conductive constituent. The method further includes the step of infiltrating
the skeleton with an infiltration material to obtain the contacts material.
[0013] These and other objects of this invention can also be achieved by providing a method
of manufacturing the contacts material as described above including the steps of manufacturing
a skeleton with the arc-proof constituent and infiltrating the skeleton with an infiltration
material to obtain the contacts material. The infiltration material includes the conductive
constituent added with the auxiliary constituent.
[0014] These and other objects of this invention can further be achieved by providing a
method of manufacturing the contacts material as described above including the step
of mixing powders of the arc-proof constituent, the auxiliary constituent and the
conductive constituent to form a mixed contacts material powder. The method further
includes the steps of forming the mixed contacts material powder to form a molded
body and sintering the molded body to obtain the contacts material.
[0015] Specifically, the reason why the adhesion between the arc-proof constituent and the
conductive constituent in the contacts material is increased by the addition of the
auxiliary constituent to the arc-proof constituent and conductive constituent is described
below. In the case of the conventional contacts material, in which the arc-proof material
such as tungsten is employed, insufficient interface strength was obtained owing to
its complete failure to form a solid solution with or to react with conductive constituent
such as copper. In the case of the contacts material of this invention there is added
the auxiliary constituent that reacts with the arc-proof material and also reacts
with the conductive constituent. As a result, the arc-proof constituent and conductive
constituent are more tightly adhered, so that restriking can be prevented, because
a reduction is achieved in discharge from the surface of the arc-proof grains, generation
of marked unevenness on occurrence of welding, and pores in the interior of the contacts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete appreciation of the invention and many of the attendant advantages
thereof will be readily obtained as the same becomes better understood by reference
to the following detailed description when considered in connection with the accompanying
drawings, wherein:
Fig. 1 is a cross-sectional view of a vacuum valve to which a contacts material for
the vacuum valve according to this invention is applied; and
Fig. 2 is an enlarged cross-sectional view of the electrode portion of the electrode
portion of the vacuum value shown in Fig. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Embodiments of this invention are described below with reference to the drawings.
Fig. 1 is cross-sectional view of a vacuum valve. Fig. 2 is a view to a larger scale
of the electrode portion of the vacuum valve shown in Fig. 1.
[0018] In Fig. 1, a circuit breaking chamber 1 is constituted by an insulating vessel 2
formed practically on a cylinder by insulating material and metal covers 4a, 4b provided
at both ends thereof, with interposition of sealing fitments 3a and 3b, the chamber
being maintained under vacuum.
[0019] Circuit breaking chamber 1 has arranged within it a pair of electrodes 7 and 8 mounted
at facing ends of conductive rods 5 and 6. For example upper electrode 7 is the fixed
electrode, while lower electrode 8 is the movable electrode. A bellows 9 is fitted
to conductive rod 6 of this electrode 8, so that movement in the axial direction of
electrode 8 can be performed whilst maintaining vacuum-tightness within circuit breaking
chamber 1. A metal arc shield 10 is provided at the top of the bellows 9 to prevent
bellows 9 being covered by arc vapour. A metal arc shield 11 is provided in circuit
breaking chamber 1 so as to cover electrodes 7 and 8, to prevent insulating vessel
2 being covered by arc vapour.
[0020] As shown in Fig. 2, electrode 8 is fixed to conductive rod 6 by a brazing portion
12, or is press-fitted by caulking. A contact 13a is mounted on electrode 8 by brazing
a portion 14. Essentially the same construction is adopted for electrode 7, having
contact 13b.
[0021] Next, examples of a method of manufacturing contacts material according to this invention
will be described. Methods of manufacturing contacts material can be broadly classified
into the infiltration method, wherein the conductive constituent is melted and allowed
to flow into a skeleton formed of the arc-proof powder etc., and the sintering method,
in which the powders are mixed in prescribed proportions and molded and sintered.
[0022] Compared with the prior art methods, the method of manufacture according to this
invention has the following characteristics. Specifically, in the case of the infiltration
method, the characteristic feature is that a skeleton is manufactured by sintering
in for example vacuum atmosphere a mixed powder consisting of the arc-proof powder
and the third element powder (auxiliary constituent powder), and the conductive constituent
is infiltrated into this skeleton in for example a vacuum atmosphere to manufacture
contacts material. It is also possible to manufacture the contacts material by infiltrating
conductive constituent, to which the third element has been added, into a skeleton
manufactured of arc-proof powder only. In the case of the sintering method, the characteristic
feature is that the contacts material is manufactured by sintering for example in
vacuum atmosphere a mixed powder consisting of arc-proof powder, conductive powder
and third element powder blended in prescribed amounts. In both the infiltration and
sintering methods, the contacts can be manufactured using a composite powder obtained
by coating the surface of the arc-proof constituent powder with the third element,
or an alloy powder of the arc-proof element and the third element.
[0023] Next, a method of evaluation and the conditions for the evaluation will be explained,
whereby concrete examples, to be described, are obtained. With the above described
matters in view, a comparison was made between contacts material according to this
invention and conventionally manufactured contacts material, in terms of frequency
of occurrence of restriking. The disc-shaped sample of contacts material of diameter
30 mm, thickness 5 mm is fitted in a demountable-type vacuum valve. And then, measurements
were carried out by measuring the frequency of occurrence of restriking on breaking
a 60 kV × 500A circuit 2000 times by the demountable-type vacuum valve. The results
were expressed as a percentage occurrence of restriking. For fitting the contacts,
only baking heating (450°C × 30 minutes) was performed. Brazing material was not used,
and the heating which would accompany this was not performed.
Table 1
|
Chemical constituents (vol%) |
Percentage occurrence of restriking |
Method of manufacture |
Notes |
|
Nb |
Cr |
Cu |
|
|
|
Comparative example 1 |
25 |
0 |
Bal |
1 - 2% |
sintering |
|
Example 1 |
25 |
1 |
Bal |
0.8% |
sintering |
|
Example 2 |
25 |
25 |
Bal |
0.5% |
infiltration |
|
Example 3 |
25 |
50 |
Bal |
0.5% |
infiltration |
|
Comparative example 2 |
25 |
65 |
Bal |
0.8% |
infiltration |
Large contact resistance |
Table 2
|
Chemical constituents (vol%) |
Percentage occurrence of restriking |
Method of manufacture |
Notes |
|
Ta |
Ti |
Cu |
|
|
|
Comparative example 3 |
15 |
1 |
Bal |
0.8% |
sintering |
insufficient breaking ability |
Example 4 |
25 |
1 |
Bal |
0.8% |
sintering |
|
Example 5 |
50 |
1 |
Bal |
0.5% |
infiltration |
|
Example 6 |
70 |
1 |
Bal |
0.5% |
infiltration |
|
Comparative example 4 |
90 |
1 |
Bal |
0.8% |
infiltration |
Large contact resistance |
Table 3
|
Chemical constituents (vol%) |
Percentage occurrence of re-restriking |
Method of manufacture |
|
W |
Mo |
Y |
Zr |
Co |
Cu |
Ag |
|
|
Example 7 |
50 |
0 |
0 |
0 |
5 |
30 |
15 |
0.8% |
infiltration |
Example 8 |
25 |
25 |
1 |
1 |
0 |
Bal |
0 |
0.5% |
infiltration |
Table 4
|
Chemical constituents (vol%) |
Method of manufacture |
Percentage of restriking |
Example 9 |
45Nb-5Cr-Cu |
sintering |
0.5% |
Example 10 |
45Nb-1Cr-Cu |
sintering |
0.5% |
Example 11 |
20Nb-20Cr-Cu |
sintering |
0.5% |
Example 12 |
25Nb-3Cr-Cu |
sintering |
0.8% |
[0024] In the manufacture of Table 1 through Table 3, a single metal powder was employed.
The skeleton for the infiltration method was manufactured only of arc-proof powder
and auxiliary constituent powder. Oxygen-free copper and vacuum-melted Ag/Cu alloy
were employed as infiltration material.
Examples 1 - 3, Comparative Examples 1 - 2 (refer to Table 1)
[0025] Contacts were manufactured with the niobium content of the arc-proof material fixed
at 25 volume % but with added amounts of the chromium auxiliary constituent of 0,
1, 25, 50 and 65 volume % (comparetive example 1, examples 1, 2 and 3 and comparative
example 2, respectively). The raw material powder used consisted of a mixture of niobium
powder and chromium powder. Comparative example 1 and example 1 were manufactured
by the sintering method. In more detail, manufacture was carried out by sintering
at prescribed temperature after mixing and molding niobium powder, chromium powder
and copper powder to prepare samples to be tested. The detailed conditions for manufucturing
these samples are described as CONDITION 1.
CONDITION 1 for Example 1 and Comparative Example 1
[0026] A Nb powder, a Cr powder and a Cu powder having an average grain size of 100, 50
and 30 micrometers, respectively, are provided. These are mixed for 12 hours in a
ball mill. The resulting mixture is molded with a molding pressure of 8 metric tons
per square centrimeter. The resulting molded body is sintered at a temperature of
1050°C for 3 hours under a vacuum of 1.0 × 10⁻² Pa to obtain the sample of the contacts
material.
[0027] Examples 2 and 3 and comparative example 2 were manufactured by the infiltration
method. In more detail, a skeleton was manufactured by mixing, forming and sintering
niobium powder and chromium powder. Next, samples were prepared by infiltration of
oxygen-free copper into the skeleton. The detailed conditions for manufacturing these
samples are described as CONDITION 2.
CONDITION 2 for Examples 2 and 3 and Comparative Example 2
[0028] A Nb powder and a Cr powder having an average grain size of 100 and 50 micrometers,
respectively, are provided. These are mixed for 12 hours in a ball mill. The resulting
mixture is molded with a molding pressure of 0.5, 2 and 5 metric tons per square centimeter,
for example 2, example 3 and comparative example 2, respectively. The resulting molded
body is sintered at a temperature of 1200°C for 1 hours under a vacuum of 1.0 × 10⁻²
Pa to obtain a skeleton. The skeleton is infiltrated by oxygen-free copper at a temperature
of 1130°C for 0.5 hour under a vacuum of 1.0 × 10⁻² Pa to obtain the sample of the
contacts material.
[0029] The probability of occurrence of restriking was measured after processing these samples
and mounting them in a demountable-type vacuum valve. As shown in Table 1, the result
was that, whereas in comparative example 1, in which no chromium was added, the probability
of occurrence of restriking was 1 - 2%, in examples 1, 2, and 3, in which 1, 25 and
50% chromium was added, it was 0.5 - 0.8%, representing an improvenent. The probability
of occurrence of restriking, at 0.8%, was also improved in the case of comparative
example 2, in which 65% chromium was added. But this comparative example 2 is problematic
in practical use because it has a large contact resistance owing to the dearth of
conductive constituent. For purpose of comparison, an attempt was also made to manufacture
Nb-Cu contacts material by the infiltration method with no chromium addition. However,
perhaps infiltration could not be achieved due to the effect of surface oxide.
Examples 4 - 6, Comparative Examples 3 - 4 (see Table 2)
[0030] Contacts materials were manufactured with the addition of the auxiliary constituent
titanium fixed at 1 volume % but with contents of the arc-proof constituent tantalum
of 15, 25, 50, 70 and 90 volume % (comparative example 3, examples 4, 5 and 6 and
comparative example 4, respectively). In the case of comparative example 3 and example
4, the method of manufacturing the contacts material was the sintering method. The
detailed conditions for manufacturing these samples are described as CONDITION 3.
CONDITION 3 for Example 4 and Comparative Example 3
[0031] A Ta powder, a Ti powder and a Cu powder having an average grain size of 100, 50
and 30 micrometers, respectively, are provided. The following process is the same
as that of the CONDITION 1.
[0032] In the case of examples 5 and 6 and comparative example 4, the infiltration method
was employed. The detailed conditions for manufacturing these samples are described
as CONDITION 4.
CONDITION 4 for Examples 5 and 6 and Comparative Example 4
[0033] A Ta powder and a Ti powder having an average grain size of 100 and 50 micrometers,
respectively, are provided. These are mixed for 12 hours in a ball mill. The resulting
mixture is molded with a molding pressure of 0.5, 2 and 5 metric tons per square centimeter,
for example 5, example 6 and comparative example 4, respectively. The following process
is the same as that of the CONDITION 2.
[0034] In the case of all the samples, an improvement in respect of the restriking probability
was seen, this being 0.5 - 0.8%. However, in the case of comparative example 3, in
which the tantalum content was 15%, the circuit-breaking capability was much decreased,
and in the case of comparative example 4 in which the tantalum content was 90%, the
contact resistance became large as in comparative example 2 referred to above, to
the extent that this sample could not be incorporated in a practical vacuum valve.
Examples 7 - 8 (see Table 3)
[0035] In Table 1 examples using Nb - Cr - Cu systems and in Table 2 examples using Ta -
Ti - Cu system were described. However, reduction in the restriking probability can
likewise be obtained by the use of tungsten and molybdenum as arc-proof material instead
of niobium and tantalum, and by the use of yttrium, zirconium, cobalt or vanadium
as auxiliary constituent instead of chromium or titanium. Also silver could be used
as conductive constituent instead of copper. Example 7 is an example in which contacts
consisting of 50 volume % W - 5% Co - 30% Cu - 15% Ag were manufactured by the infiltration
method. Example 8 is an example in which contacts consisting of 25% W - 25% Mo - 1%
Y - 1% Zr-Cu (Balance) were manufactured by the infiltration method. The detailed
conditions for manufacturing these samples are described as CONDITION 5.
CONDITION 5 for Examples 7 and 8
[0036] A W powder, a Co powder, a Cu powder and an Ag powder having an average grain size
of 3, 5, 30 and 30 micrometers, respectively, are provided for example 7. A W powder,
a Mo powder, a Y powder, a Zr powder and a Cu powder having an average grain size
of 3, 3, 30, 30 and 30 micrometers, respectively, are provided for example 8. The
following process is the same as that of the example 2 in the CONDITION 2. Both of
these contacts were useful as they offered low restriking probabilities of 0.8% and
0.5%.
[0037] From the results of examination of the above examples it can be seen that the frequency
of restriking can be reduced not merely by the compositions of the example but by
employing tantalium, niobium, molybdenum or tungsten as arc-proof material, chromium,
titanium, yttrium, zirconium, cobalt or vanadium as auxiliary constituent, and copper
or silver as conductive constituent.
Examples 9 - 12 (see Table 4)
[0038] Next, the method of manufacture will be examined. Example 9 is an example in which
a skeleton was manufactured by blending and mixing niobium powder and chronium poweder
in the ratio 9:1 and this was then infiltrated with oxygen-free copper. Example 10
is an example in which a skeleton was manufactured consisting of niobium powder only,
and this was then infiltrated with a previously prepared 2% Cr - Cu alloy. Example
11 is an example in which a skeleton was prepared by mixing and sintering Nb/Cr alloy
powder with Cu powder and this was then infiltrated with further oxygen-free copper.
In example 12, contacts were manufactured by coating the surface of niobium powder
with chromium and then mixing this with copper powder and molding, followed by sintering.
[0039] The detailed conditions for manufacturing these samples are described as CONDITIONs
6, 7, 8 and 9.
CONDITION 6 for Example 9
[0040] A Nb powder and Cr powder having an average grain size of 100 and 50 micrometers,
respectively, are provided. The Nb powder and the Cr powder are blended in the ratio
of 9:1 by volume and then mixed for 12 hours in a ball mill. The resulting mixture
is molded with a molding pressure of 0.5 metric tons per square centimeter. The resulting
molded body is sintered at a temperature of 1200°C for 3 hours under a vacuum of 1.0
× 10⁻² Pa to obtain a skeleton. The skeleton is infiltrated by oxygen-free copper
at a temperature of 1130°C for 0.5 hour under a vacuum of 1.0 × 10⁻² Pa to obtain
the sample of the contacts material.
CONDITION 7 for Example 10
[0041] A Nb powder having an average grain size of 100 micrometers is molded with a molding
pressure of 0.5 metric tons per square centimeter. The resulting molded body is sintered
at a temperature of 1200°C for 3 hours under a vacuum of 1.0 × 10⁻² Pa to obtain a
skeleton. 2% Cr - Cu alloy is prepared by melting Cr and Cu under a vacuum of 1.0
× 10⁻² Pa, in advance. The skeleton is infiltrated by 2% Cr - Cu alloy at a temperature
of 1130°C for 0.5 hour under a vacuum of 1.0 × 10⁻² pa to obtain the sample of the
contacts material.
CONDITION 8 for Example 11
[0042] 50 wt% - Cr alloy is crushed into an alloyed powder having an average grain size
of 100 micrometers. The alloyed powder and a Cu powder having an average grain size
of 30 micrometers are mixed for 12 hours in a ball mill. The resulting mixture is
molded with a molding pressure of 3 metric tons per square centimeter. The resulting
molded body is sintered at a temperature of 1200°C for 1 hour under a vacuum of 1.0
× 1.0⁻² Pa to obtain a skeleton. The skeleton is infiltrated by oxygen-copper at a
temperature of 1130°C for 0.5 hour under a vacuum of 1.0 × 10⁻² Pa to obtain the sample
of the contacts material.
CONDITION 9 for Example 12
[0043] A Nb powder having an average grain size of 100 micrometers is coated with Cr to
form a composite powder, in which Nb and Cr are in the ratio of 9:1 by volume. The
composite powder and a Cu powder having an average grain size of 30 micrometers are
mixed for 12 hours in a ball mill. The resulting mixture is molded with a molding
pressure of 8 metric tons per square centimeter. The resulting molded body is sintered
at a temperature of 1050°C for 3 hours under a vacuum of 1.0 × 10⁻² Pa to obtain the
sample of the contacts material.
[0044] The restriking probabilities of these contacts were in each case 0.5 - 0.8% i.e.
good results were obtained.
[0045] When the cross-sectional structure of the contacts materials manufactured by these
various methods was observed using an optical microscope and an electron microscope,
it was found that in all cases the periphery of the arc-proof material tended to be
surrounded by the auxiliary constituent, confirming that the auxiliary constituent
plays the role of bonding the arc-proof material and the conductive constituent. In
particular, this trend was very noticeable in contacts material manufactured by the
infiltration method. It can be inferred that this result is reflected in the fact
that, whereas the probability of occurrence of restriking is about 0.8% in the case
of contacts material manufactured by sintering, that of contacts material manufactured
by infiltration is 0.5%. When manufacturing contacts material by the sintering method,
to suppress occurrence of restriking, it is therefore desirable to have the sintering
temperature to be as close to the melting point as possible. But contacts material
even manufactured by the sintering method can also lower the probability of restriking
sufficiently.
[0046] Also, on subjecting the conductive constituent matrix constructed with conductive
constituent to examination of the cross-sectional structure, it was found that in
many places the auxiliary constituent had melted or precipitated within the conductive
constituent matrix, resulting in firm adhesion between the auxiliary constituent and
the conductive constituent. This phenomenon too was found to be particularly noticeable
in contacts material produced by the infiltration method.
[0047] From the results of examination of the above examples, it is clear that, in the method
of manufacture according to this invention, similar results can be obtained not just
in the present examples but also by partial combinations of these examples.
[0048] As described above, with this invention, contacts material for a vacuum valve, and
a method of manufacturing it, can be obtained which is of high reliability and whereby
the probability of restriking is reduced, owing to the increased strength of adhesion
between arc-proof constituent and conductive constituent which is obtained thanks
to the auxiliary constituent.
[0049] Obviously, numerous modifications and variations of the present invention are possible
in light of the above teachings. It is therefore to be understood that within the
scope of the appended claims, the invention may be practiced otherwise than as specifically
described herein.
1. A contacts material for a vacuum valve, comprising:
an arc-resistant or arc-proof constituent comprising at least one of:
tanatalum, niobium, tungsten and molybdenum;
an auxiliary constituent comprising at least one of:
chromium, titanium, yttrium, zirconium, cobalt and vanadium; and
a conductive constituent comprising:
copper and/or silver;
the amount of said arc-resistant or arc-proof constituent being from 25% to 75%
by volume;
the total amount of said arc-resistant or arc-proof constituent together with said
auxiliary constituent being no more than 75% by volume; and
the amount of said conductive constituent being the balance.
2. A contacts material according to claim 1, wherein:
said auxiliary constituent is formed to surround a periphery of said arc-resistant
or arc-proof constituent; and
said conductive constituent is contained in the form of a conductive constituent
matrix.
3. A contacts material according to claim 1, wherein:
said arc-resistant or arc-proof constituent and said auxiliary constituent are
formed in an alloy; and
said conductive constituent is contained in the form of a conductive constituent
matrix.
4. A contacts material according to claim 2 or 3, wherein:
said auxiliary constituent is melted within said conductive constituent matrix.
5. A contacts material according to claim 2 or 3, wherein:
said auxiliary constituent is precipitated within said conductive constituent matrix.
6. A method of making a contacts material as defined in claim 1, comprising the steps
of:
manufacturing a skeleton with said arc-resistant or arc-proof constituent and said
auxiliary constituent; and
infiltrating said skeleton with an infiltration material to obtain said contacts
material.
7. A method of making a contacts material as defined in claim 1, comprising the steps
of:
manufacturing a skeleton with said arc-resistant or arc-proof constituent, said
auxiliary constituent and said conductive constituent; and
infiltrating said skeleton with an infiltration material to obtain said contacts
material.
8. A method according to claim 6 or 7, wherein:
said infiltration material includes said conductive constituent.
9. A method according to any one of claims 6 to 8, wherein:
said infiltration material includes said conductive constituent added with said
auxiliary constituent.
10. A method according to any one of claims 6 to 9, wherein:
in the step of manufacturing said skeleton, a powder of said arc-resistant or arc-proof
constituent and a powder of said auxiliary constituent are mixed to form a mixed powder,
and said skeleton is manufactured with said mixed powder.
11. A method according to any one of claims 6 to 10, wherein:
in the step of manufacturing said skeleton, a composite powder of said arc-proof
constituent surrounded by said auxiliary constituent is prepared, and said skeleton
is manufactured with said composite powder.
12. A method according to any one of claims 6 to 11, wherein:
in the step of manufacturing said skeleton, an alloy powder of said arc-proof constituent
and said auxiliary constituent is prepared, and said skeleton is manufactured with
said alloy powder.
13. A method of making a contacts material as defined in claim 1, comprising the steps
of:
manufacturing a skeleton with said arc-resistant or arc-proof constituent; and
infiltrating said skeleton with an infiltration material to obtain said contacts
material;
said infiltration material including said conductive constituent added with said
auxiliary constituent.
14. A method of making a contacts material as defined in claim 1, comprising the steps
of:
mixing powders of said arc-resistant or arc-proof constituent, said auxiliary constituent
and said conductive constituent to form a mixed contacts material powder;
moulding said mixed contacts material powder to form a moulded body; and
sintering said moulded body to obtain said contacts material.
15. A method according to claim 14, wherein:
in the step of mixing, said powder of said arc-resistant or arc-proof constituent
and said powder of said auxiliary constituent are mixed to form a mixed powder, and
said mixed powder and said powder of said conductive constituent are mixed to form
said mixed contacts material powder.
16. A method according to claim 14, wherein:
in the step of mixing, a composite powder of said arc-proof constituent surrounded
by said auxiliary constituent is prepared, and said composite powder and said powder
of said conductive constituent are mixed to form said mixed contacts material powder.
17. A method according to any one of claims 14 to 16, wherein:
in the step of mixing, an alloy powder of said arc-proof constituent and said auxiliary
constituent is prepared, and said alloy powder and said powder of said conductive
constituent are mixed to form said mixed contacts material powder.
18. A vacuum valve which includes contacts formed from a material as defined in any one
of claims 1 to 5.